Characteristics

• This is a rare disease of unknown cause characterised by the presence of abnormal smooth muscle proliferation of the pulmonary interstitium, particularly in the bronchioles, pulmonary vessels and lymphatics.

• Exclusively affects women of a child-bearing age.

• Associated with chylous ascites, fatty liver and renal angiomyolipomas.

Clinical features

• Progressive exertional dyspnoea.

• Haemoptysis.

• Restrictive lung function and hypoxia.

• Increase in symptoms during pregnancy and on the oral contraceptive pill.

Radiological features

• CXR – coarse reticular interstitial pattern with cyst formation on the background of large volume lungs. There is a common association with chylous pleural effusions (70%), pneumothoraces (40%) and mediastinal lymphadenopathy.

• HRCT – numerous random thin-walled cysts of varying size and relatively regular shape. Bronchovascular bundles at edge of cyst. Lymphadenopathy, pleural effusions and pneumothoraces. Dilated thoracic duct.

• Long-standing cases may develop pulmonary arterial hypertension with enlargement of the central pulmonary arteries.

Differential diagnosis

• Langerhan's cell histiocytosis – male smokers, with upper zone predisposition and more cyst irregularity.

• Tuberous sclerosis – rare. Other characteristic abnormalities present.

• Emphysema – smokers. No wall to the emphysematous bullae.

• Neurofibromatosis – rare with musculoskeletal and neurogenic abnormalities.

• Lung fibrosis (e.g. UIP). Basal fibrosis and honeycombing.

Management

• Lung biopsy may be required to confirm the diagnosis.

• No specific treatment.

• 10-year survival is 75%.

• Progression to pulmonary insufficiency and arterial hypertension.